Employment Tribunal Time Limits: How the 3-Month Rule and ACAS Conciliation Work

Employment Tribunal Time Limits and ACAS

When you think you have been treated unfairly at work, the first thing to check is time. Most tribunal claims have a short deadline, and a missed one usually ends the claim whatever its merits. The Employment Tribunal Time Limit and ACAS Calculator counts the dates, including the pause for early conciliation.

The basic rule

For most claims, including unfair dismissal, discrimination and unlawful deductions from wages, the claim must be made within three months less one day from the date of the act you complain about. If you were dismissed on 14 August, the last day is 13 November. For a dismissal, the date is the effective date of termination, which may be earlier than your last day of pay. The government has legislated to lengthen the period for many claims to six months from a date set by regulations, so check which period applies to your claim; the tool lets you choose.

Early conciliation

With few exceptions you must contact ACAS before you start a tribunal claim, so that it can offer to help you and your employer settle. The date on which ACAS receives your notification is Day A. If conciliation ends without settlement, ACAS issues a certificate on Day B. You need the certificate number to make your claim.

How the clock stops

The days between Day A and Day B are not counted. After Day B you have at least one month. If the normal limit would have run out between Day A and one month after Day B, the deadline becomes one month after Day B. If the normal limit would have run out later, you add the number of days between Day A and Day B to the original deadline. If you contact ACAS after the normal limit has already ended, early conciliation does not give you more time.

Using the calculator

Enter the date of the event and choose the time limit. If you have already been in contact with ACAS, enter Day A and Day B. The tool shows the normal limit, which case applies, the deadline and the days left, with a warning if ACAS was contacted too late.

Examples

For an event on 14 August 2026, the normal limit ends on 13 November. If ACAS is notified on 1 September and the certificate issues on 1 October, one month after Day B is 1 November. The normal limit (13 November) is later, so 30 days are added: the deadline is 13 December 2026. If ACAS is notified on 2 November and the certificate issues on 20 November, the limit would have run out during the process, so the deadline is one month after Day B, which is 20 December 2026.

What if you are late

A tribunal can hear a late claim only if it was not reasonably practicable to make it in time, and you made it within a reasonable time afterwards, or for discrimination claims if it is "just and equitable". These are hard tests. Ill health, waiting for an internal appeal or a lack of knowledge of the deadline rarely help. Do not delay.

Practical steps

Write the date down, contact ACAS early, and keep the notification and certificate. Gather your evidence: contract, emails, letters and notes of meetings. Consider advice from a union, a Citizens Advice office or a solicitor, many of whom offer a free first meeting. Check whether other deadlines apply, for example for redundancy payments or a breach of contract claim.

Limits

This is a date tool and not legal advice. The law is changing, so always check the current rules on GOV.UK.